1. Field of the Invention
The present invention is directed to a tufting machine, and more particularly, an improved feed roller assembly for a tufting machine.
2. Description of the Related Art
Tufting machines are widely used for manufacturing tufted pile fabrics, such as carpeting. Many tufting machines include yarn feed roller pattern attachments or assemblies configured to produce variations in pile height of the carpet products.
Yarn feed roller assemblies typically include groups of yarn feed rollers which are driven at different speeds. The rollers in each group are arranged parallel to each other and are closely spaced. An array of strands of yarn are guided across each group of rollers.
Pattern attachments known as xe2x80x9cfull repeat scrollsxe2x80x9d include an array of yarn wheels rotatably mounted adjacent to each roller. One yarn wheel is provided for each strand of yarn guided across each roller. The yarn wheels are movable in and out of engagement with the yarn. In the engaged position, the yarn wheel presses the yarn against the roller. Thus, because the yarn roller is driven, the yarn roller pulls the yarn into the tufting machine.
The yarn wheels can be independently driven. Additionally, the yarn rollers can be driven at different speeds. Thus, by driving the yarn wheels into and out of engagement with different rollers, adjacent strands of yarns can be fed at different rates. Additionally, the feed rate of a single strand of yarn can be changed quickly. Different feeding rates result in different pile heights in the resulting carpet product.
Examples of such machines are sold under the trademark Cobble(trademark). These machines can be configured to provide two or three different pile heights in a carpet. Additionally, these machines can be configured to produce rolls of carpet approximately 13 feet wide. In such machines, the yarn rollers are made from metal shafts approximately four meters long.
In order to prevent bending and vibration of the feed rollers during operation, the scroll attachments are divided into a number of parallel yarn feeding bays. In one example, the bays are approximately 24 inches wide and are separated by bearing supports. Thus, each shaft is supported by 8 bearing supports. The bearing supports include recesses for receiving roller bearings which are mounted to each shaft in an known manner.
The shafts are made out of a strong metal material such as steel. The outer surface of the rollers, however, is covered with a softer material which provides a desired friction against the strands of yarn so as to transfer the rotational movement of the shaft to a linear displacement of the yarn strands. One type of covering that is commonly used is known as xe2x80x9cNorthrop Type LHP.xe2x80x9d
As a result of prolonged operation, the outer covering of the rollers can become worn or damaged. For example, the covering can be damaged to the point where the covering loses the ability to provide traction against the yarn. Thus, the yarn disposed in contact with that portion of the covering will not be fed properly. The resulting carpet product will have a visible flaw.
In order to allow the covering to be replaced, the covering can be procured in a roll having a narrow width, such as, for example, 2 inches wide. After the original covering has been removed, replacement covering can be re-applied by rotating the feed roller and wrapping the covering in a helical pattern around the outer surface of the roller.
This manner of replacing the outer surface of the roller allows the roller to remain installed on the tufting machine without having to remove the numerous strands of yarn from the machine. However, this process of resurfacing the feed rollers produces a length of carpet product that is unacceptable for resale. Thus, the roll of carpet being produced at that time must be cut so as to remove the unacceptable portion. Further, the roll of carpet being manufactured will not be of a standard length and thus would be resold as a remnant, or xe2x80x9codd sizexe2x80x9d and thus is usually sold for less than full price.
Another common repair performed on tufting machines, and in particular, full repeat scroll attachments, is related to the yarn wheels. As noted above, the yarn wheels are driven into and out of engagement with the feed rollers. Occasionally, a bearing which rotatably journals the yarn wheel fails. This failure results in an improper feeding speed of a particular strand of yarn. When a yarn wheel bearing fails, the feed rollers have to be dislodged so that the yarn wheels can be removed. In certain full repeat scroll attachments, the bearing support assemblies for the feed rollers are hingedly mounted to a frame. Thus, the feed rollers can be dislodged by removing two bolts from each bearing support assembly so that the bearing support assemblies can be pivoted about their respective hinges. For a machine with seven bays, 16 bolts have to be removed before the feed rollers can be pivoted, i.e., two bolts for each bearing support assembly.
Another common component to fail on tufting machines is the feed roller bearings. Known feed rollers are formed from a single steel shaft having a number of bearings press fit thereon. Additionally, as noted above, the portions of the shaft between the bearings are covered with a soft outer covering to provide friction against the yarn. Thus, when one of the bearings fails, the entire shaft must be removed, as well as the outer covering of the shaft, so that the damaged bearing can be removed. If the damaged bearing is near the center of the shaft, adjacent bearings also must be removed so that the damaged bearing can be removed.
One aspect of the present invention includes the realization that certain repairs to known full repeat scroll attachments can be made more quickly if portions of the feed roller can be removed or dislodged independently without the need to remove or dislodge the entire feed roller.
Another aspect of the present invention includes the realization that several of the drawbacks the of prior art spiral-wound yarn roller coverings can be overcome by using a vulcanized covering. For example, when the prior art helical covering is applied to a yarn roller, the covering should be applied so that adjacent edges of the windings are as close as possible. However, when this type of covering is applied during maintenance of a used tufting machine, the covering is applied by hand, while the shaft is in place with two arrays of yarn strands extending in front of and behind the shaft. Thus, at least slight imperfections in the spacing of the windings of the covering are inevitable. A vulcanized covering, however, provides substantially seamless outer surface, and thus, does not suffer from the problems caused by the presence of a helical seam on the outer surface of the roller.
In accordance with yet another aspect of the present invention, a tufting machine comprises a frame assembly, and a plurality of parallel yarn feeding bays supported by the frame. An inlet yarn guide is supported by the frame and is configured to guide a plurality of yarn strands into each of the bays. A needle assembly is supported by the frame and is configured to reciprocate relative to the frame. An outlet yarn guide is configured to guide the yarn strands from the bays into the needle assembly. The tufting machine also includes first and second feed roller assemblies, each extending across all of the bays. At least first and second bearing assemblies support both of the first and second feed roller assemblies. Each of the first and second bearing assemblies are disposed between two of the bays. First and second drives are configured to drive the first and second feed roller assemblies, respectively, such that the first feed roller assembly is driven at a speed greater than a speed of the second feed roller assembly. First and second wheels mounted adjacent the first and second feed roller assemblies, respectively, and are moveable between first and second configurations. In the first configuration, the first wheel presses a first yarn strand against the first feed roller. In the second configuration, the second wheel presses the first yarn strand against the second feed roller. Each roller assembly comprises at least first and second coaxially aligned cylindrical members, each having a terminal end disposed in the vicinity of one of the bearing assemblies which are disposed between two bays.
In accordance with a further aspect of the present invention, a tufting machine comprises at least two parallel yarn feeding bays. At least one bearing support assembly is disposed between the bays. At least one feed roller assembly extends across the bays. A plurality of wheels are moveable into and out of engagement with the feed roller assembly. The feed roller assembly comprises a plurality of co-axially aligned rollers being separable at a position in the vicinity of the bearing support assembly.
In accordance with yet another aspect of the present invention, a tufting machine comprises at least first, second, and third parallel yarn feeding bays. The second bay is between the first and second bays. At least one roller assembly extends across all three bays. At least one wheel is moveable into and out of engagement with the roller assembly. The feed roller assembly comprising first, second, and third feed rollers aligned with the first, second, and third bays, respectively. Additionally, the machine includes means for allowing the second roller to be removed without removing the first and third rollers.
In accordance with another aspect of the present invention, a tufting machine comprises a plurality of parallel yarn feeding bays. At least one roller assembly extends across all three bays, the feed roller assembly comprises a vulcanized outer covering.